Our research will attempt to elucidate the structural basis underlying normal and altered renal function. Experiments on glomerular permeability and structure will concentrate on the effect of molecular charge on glomerular permeability to proteins, alteration in glomerular polyanion that may underlie proteinuria, cytochemical characterization of glomerular polyanion, and the role played by polyanions in the maintenance of normal glomerular structure. Experiments on acute renal failure will focus on vascular and tubular pathology during the recovery phase of the disease, and mechanisms of tubular backleak and obstruction in the ischemic model. Studies on the renal medullar will include observations on thin limb ultrastructure in the rat and desert rodents and the morphology of renal collecting duct and papillary epithelium in diabetes insipidus rats. Methods used are transmission, freeze fracture and scanning electron microscopy, in vitro perfusion methods, gel filtration and ion exchange chromatography, isoelectric focusing, tracer techniques including histochemistry, freeze substitution and morphometry. BIBLIOGRAPHIC REFERENCES: Rennke, H.G., Cotran, R.S. and Venkatachalam, M.A.: Role of molecular change in glomerular permeability: Tracer studies with cationized ferritins. J. Cell. Biol. 67:638-646, l976. Venkatachalam, M.A., Rennke, H.G., and Sandstrom, D.J.: The vascular basis for acute renal failure in the rat: Preglomerular and post glomerular vasoconstriction. Circ. Res. 38:267-279, l976.